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    <script>
        function fn1() { console.log(1) };

        function fn2() { console.log(2) };

        fn3 = fn2.call;

        fn2.call(fn1);//请问输出什么结果，为什么
        //2

        fn3.call(fn1);//请问输出什么结果，为什么
        //1

        fn3.call.call(fn1);//请问输出什么结果，为什么
        //1
    </script>
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